CN104515980A - Method and device for ground moving target indication based on InSAR (interferometric synthetic aperture radar) formation - Google Patents

Abstract

The invention discloses a method and a device for ground moving target indication based on InSAR (interferometric synthetic aperture radar) formation. The method includes: setting up a sliding spotlight SAR echo model according to original echo signals received in a scene irradiation region, and imaging each single radar two-dimensional sliding spotlight initial SAR image in the model; enabling the plurality of imaged radar initial SAR images to form a three-dimensional matrix, and subjecting sections of the three-dimensional matrix to compressed sensing treatment to acquire SAR images; subjecting the SAR images to registration, wherein same pixels in different SAR images correspond to a same ground unit; subjecting the registered SAR images to space-time adaptive processing; subjecting the SAR images to elevation phase compensation after space-time adaptive processing; subjecting the SAR images to target detection after elevation phase compensation by means of constant false alarm rate detection. By means of elevation phase compensation, measurement accuracy can be evidently improved, and measurement errors can be controlled about 0.05.

Description

A kind of Ground moving target detection method and apparatus based on InSAR configuration

Technical field

The present invention relates to Ground moving target detection technical field, particularly, relate to a kind of Ground moving target detection method and apparatus based on InSAR configuration.

Background technology

Ground moving target detection (GMTI, Ground Moving Target Indication) militarily has special important meaning, is the focal issue that people pay close attention to always.Traditional single star space based radar, owing to being subject to the restriction of base length, constrains the performance of its GMTI greatly.Interference synthetic aperture radar (InSAR, Interferometric Synthetic Aperture Radar) system has the feature of Long baselines and many baselines, achieve to the high precision imaging of target floor three-dimensional landform with to ground moving object high precision test, moving target can be detected while acquisition elevation information, and have a clear superiority at detection low-speed motion target side mask due to it, make to do in conjunction with InSAR the importance that Ground moving target detection becomes research both at home and abroad.

The correlative study carrying out GMTI at present under InSAR configuration has: based on the Ground moving target detection method (the TechSat21 plan of the U.S.) of Distributed Small Satellite; Utilize InSAR configuration to have the advantage of singly navigating, and Long baselines and many baselines can be provided, reduce the Minimum detectable (MDV) of Ground moving targets detection; The concept of motive target imaging is introduced thus the method for raising rate accuracy in InSAR-GMTI processing procedure.But the robustness problem of moving-target speed-position detection when above-mentioned disposal route all seldom takes into full account the clutter recognition that brings due to longer vertical parallax and there is registration error, as Clutter Degrees of Freedom increases greatly with topographic relief.

Summary of the invention

The present invention is to not take into full account that the clutter recognition etc. brought in longer vertical parallax causes the defect that robustness is not high when overcoming Ground moving target detection in prior art, according to an aspect of the present invention, a kind of Ground moving target detection method based on InSAR configuration is proposed.

A kind of Ground moving target detection method based on InSAR configuration that the embodiment of the present invention provides, comprise: set up Sliding spotlight SAR echo model according to the original echoed signals that scene irradiated site receives, and the initial SAR image of two dimension slip pack to the single radar in model; By the initial SAR image composition three-dimensional matrice of the multiple radars after imaging, compressed sensing process is carried out to three-dimensional matrice section, obtains SAR image; Carry out registration process to SAR image, the same pixel in different SAR image corresponds to same surface units; Space-time adaptive process is carried out to the SAR image after registration; Elevation phase compensation is carried out to the SAR image after space-time adaptive process; Constant false alarm rate detection technique is utilized to carry out target detection to the SAR image after elevation phase compensation.

In technique scheme, carry out registration process, comprising SAR image: utilize pixel matching method or subpixel registration method to carry out registration process to SAR image, the precision of image registration is higher than 1/10th resolution elements.

In technique scheme, space-time adaptive process is carried out to the SAR image after registration, also comprises: according to the disappear method of clutter of joint pixel pait, clutter recognition process is carried out to SAR image.

In technique scheme, elevation phase compensation is carried out to the SAR image after space-time adaptive process, comprising:

Carry out elevation phase compensation according to two width SAR image, two width SAR image interferometric phases are:

$\mathrm{\ψ}(i,j)=\mathrm{mean}\left\{\underset{m=-L}{\overset{L}{\mathrm{\Σ}}}\underset{n=-K}{\overset{K}{\mathrm{\Σ}}}\arg \right[s_1^{*}(i+m,j+n)s_2(i+m,j+n)\left]\right\}$

Wherein s ₁(i, j) and s ₂(i, j) represents the complex value of complex pattern 1 and 2 respectively, L and K representative distance to orientation to sliding window size, L=K=3.

SAR image pixel value after elevation phase compensation is:

$\hat{s}(i,j)=s(i,j)\·{\mathrm{\ψ}}^{*}(i,j).$

The present invention is to not take into full account that the clutter recognition etc. brought in longer vertical parallax causes the defect that robustness is not high when overcoming Ground moving target detection in prior art, according to an aspect of the present invention, a kind of Ground moving target detection device based on InSAR configuration is proposed.

A kind of Ground moving target detection device based on InSAR configuration that the embodiment of the present invention provides, comprising:

Slip pack module, the original echoed signals for receiving according to scene irradiated site sets up Sliding spotlight SAR echo model, and the initial SAR image of two dimension slip pack to the single radar in model;

Compressed sensing module, for the initial SAR image composition three-dimensional matrice by the multiple radars after imaging, carries out compressed sensing process to three-dimensional matrice section, obtains SAR image;

Registration module, for carrying out registration process to SAR image, the same pixel in different SAR image corresponds to same surface units;

Space-time adaptive processing module, for carrying out space-time adaptive process to the SAR image after registration;

Elevation phase compensation block, for carrying out elevation phase compensation to the SAR image after space-time adaptive process;

Module of target detection, carries out target detection for utilizing constant false alarm rate detection technique to the SAR image after elevation phase compensation.

In technique scheme, registration module specifically for: utilize pixel matching method or subpixel registration method to carry out registration process to SAR image, the precision of image registration is higher than 1/10th resolution elements.

In technique scheme, space-time adaptive processing module, also for: according to the disappear method of clutter of joint pixel pait, clutter recognition process is carried out to SAR image.

In technique scheme, elevation phase compensation block specifically for:

Carry out elevation phase compensation according to two width SAR image, two width SAR image interferometric phases are:

$\mathrm{\ψ}(i,j)=\mathrm{mean}\left\{\underset{m=-L}{\overset{L}{\mathrm{\Σ}}}\underset{n=-K}{\overset{K}{\mathrm{\Σ}}}\arg \right[s_1^{*}(i+m,j+n)s_2(i+m,j+n)\left]\right\}$

Wherein s ₁(i, j) and s ₂(i, j) represents the complex value of complex pattern 1 and 2 respectively, L and K representative distance to orientation to sliding window size, L=K=3.

SAR image pixel value after elevation phase compensation is:

$\hat{s}(i,j)=s(i,j)\·{\mathrm{\ψ}}^{*}(i,j).$

The Ground moving target detection method and apparatus based on InSAR configuration that the embodiment of the present invention provides, adopts the method for elevation phase compensation to significantly improve rate accuracy, controls range rate error about 0.05.Meanwhile, joint pixel pait is adopted to disappear the method for clutter, can clutter reduction well.

Other features and advantages of the present invention will be set forth in the following description, and, partly become apparent from instructions, or understand by implementing the present invention.Object of the present invention and other advantages realize by structure specifically noted in write instructions, claims and accompanying drawing and obtain.

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

Accompanying drawing explanation

Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for instructions, together with embodiments of the present invention for explaining the present invention, is not construed as limiting the invention.In the accompanying drawings:

Fig. 1 is the method flow diagram based on the Ground moving target detection of InSAR configuration in the embodiment of the present invention;

Fig. 2 is the range rate error Performance comparision figure with or without altimetric compensation in the embodiment of the present invention;

Fig. 3 is joint pixel pait and single pixel range rate error comparison diagram in the embodiment of the present invention;

Fig. 4 is the structural drawing based on the Ground moving target detection device of InSAR configuration in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail, but is to be understood that protection scope of the present invention not by the restriction of embodiment.

According to the embodiment of the present invention, provide a kind of Ground moving target detection method based on InSAR configuration, Fig. 1 is the process flow diagram of the method, specifically comprises:

Step 101: set up Sliding spotlight SAR echo model according to the original echoed signals that scene irradiated site receives, and the initial SAR image of two dimension slip pack to the single radar in model.

Step 102: by the initial SAR image composition three-dimensional matrice of the multiple radars after imaging, compressed sensing process is carried out to three-dimensional matrice section, obtains SAR image.

Step 103: carry out registration process to SAR image, the same pixel in different SAR image corresponds to same surface units.

Concrete, pixel matching method or subpixel registration method can be utilized to carry out registration process to SAR image, and the precision of image registration is higher than 1/10th resolution elements.

Step 104: space-time adaptive process is carried out to the SAR image after registration.

Step 105: elevation phase compensation is carried out to the SAR image after space-time adaptive process.

Step 106: utilize constant false alarm rate detection technique to carry out target detection to the SAR image after elevation phase compensation.

The Ground moving target detection method based on InSAR configuration that the embodiment of the present invention provides, adopts the method for elevation phase compensation to significantly improve rate accuracy, controls range rate error about 0.05.

Wherein, in the processing procedure of moving target detect, because InSAR configuration exists long vertical parallax, Clutter Degrees of Freedom increases greatly, traditional single pixel disappears clutter method can not good clutter reduction, so suppressed the clutter in image in step 104 by space-time adaptive process, can also comprise: according to the disappear method of clutter of joint pixel pait, clutter recognition process is carried out to SAR image.

Concrete, by echo data reconstruct as shown in Figure 2, select pixel to be detected and 8 pixels (determine according to actual conditions, also can choose by " ten " word) around, for 2 passages, arrange as follows:

x _m(i,j)＝[s _m(i,j),s _m(i-1,j-1),s _m(i-1,j),s _m(i-1,j+1),...,s _m(i+1,j+1)] ^T

Wherein (i, j) is pixel to be detected position in the picture, the data ordering of multiple passage is become the form of vector:

$X(i,j)={[x_1^T(i,j)x_2^T(i,j)...x_N^T(i,j)]}^T$

These data are vectors of dimension dimension 9N × 1.Then the covariance matrix of clutter plus noise can be written as:

R(i,j)＝E{X(i,j)X ^H(i,j)}

In formula, E{.} represents the computing asking mathematical expectation, [] ^hrepresent the conjugate transposition operation of vector.The covariance matrix R of real system is met independent identically distributed pixel data on average estimated by multiple around:

$R(i,j)=\frac{1}{\mathrm{ML}}\underset{l=-L/2}{\overset{L/2-1}{\mathrm{\Σ}}}\underset{m=-M/2}{\overset{M/2-1}{\mathrm{\Σ}}}X(i+l,j+m)X^H(i+l,j+m)$

Wherein L and M be respectively along orientation to distance to the sample number chosen; for the loss ensureing to export letter miscellaneous noise ratio is no more than 3dB (the best letter miscellaneous noise ratio relative to knowing under covariance matrix); require that ML is greater than twice degree of freedom. in moving target detect; in order to avoid echo signal contaminated sample; some protected locations can be retained when estimate covariance matrix, namely avoid pixel to be detected and the most adjacent pixel thereof when estimate covariance matrix.

Then self-adaptation weight vector W=μ R can be obtained ^-1a, wherein a is steering vector.

If the position of moving target in SAR image is (i, j), then the signal after the motive target imaging in m satellite can be written as: $s_m(i,j)=\mathrm{\σ}(i,j)\exp (-j\frac{2\mathrm{\π}}{\mathrm{\λ}}r(i,j)\exp (-j\frac{2\mathrm{\π}{v}_r(i,j)d_{\mathrm{ml}}}{\mathrm{\λ}{v}_a}))$

Wherein σ (i, j) be this moving target complex reflection coefficient, the oblique distance of r (i, j) for satellite in the imaging center moment to this target, d _m1be the center of antenna of m satellite to reference satellite center of antenna along course distance, v _afor satellite velocities, v _rfor the radial velocity of moving target.S ₁and s ₂after interfering, phase differential is can be obtained fom the above equation:

In above formula there is phase fuzzy problem, its principal value interval is [-π, π].Obtained corresponding to fuzzy speed v by (13) formula _rfor namely without the fuzzy scope of testing the speed be and by obtain blind speed $v_{\mathrm{rblind}}=n\frac{\mathrm{\λ}{v}_a}{d}.$

Concrete, SAR image, after registration process, utilizes space-time adaptive process to suppress the clutter in image.The array weight vector w of clutter reduction is by w=μ R ^-1a obtains, wherein a=[1,0 ..., 0] ^t.In theory, for the output gain of constrained motion target is constant, a should be moving target steering vector a _t.Because moving target signal can not lose, use in the embodiment of the present invention [1,0 ..., 0] replace a _t[10].Covariance matrix is estimated by independent identically distributed sample, answers reservation protection unit when choosing sample from neighbor, namely along sampling around pending pixel and most neighbor thereof this, the covariance matrix R of clutter plus noise is estimated by following formula:

$R=\frac{1}{L}\underset{l=1}{\overset{L}{\mathrm{\Σ}}}{s}_l{s}_l^H$

In formula, L (L>=2N-1) for obtain independent same distribution sample number from neighbor, s _lit is the array vector of l neighbor.

Preferably, elevation phase compensation is carried out to the SAR image after space-time adaptive process, comprising:

$\mathrm{\ψ}(i,j)=\mathrm{mean}\left\{\underset{m=-L}{\overset{L}{\mathrm{\Σ}}}\underset{n=-K}{\overset{K}{\mathrm{\Σ}}}\arg \right[s_1^{*}(i+m,j+n)s_2(i+m,j+n)\left]\right\}$

Wherein s ₁(i, j) and s ₂(i, j) represents the complex value of complex pattern 1 and 2 respectively, L and K representative distance to orientation to sliding window size, L=K=3.

SAR image pixel value after elevation phase compensation is:

$\hat{s}(i,j)=s(i,j)\·{\mathrm{\ψ}}^{*}(i,j).$

In addition, constant false alarm rate detection technique is utilized to carry out target detection to the SAR image after elevation phase compensation, and ground moving object speed-position detection.

After clutter recognition and elevation phase compensation are carried out to SAR, utilize existing CFAR technology for detection ground moving target.Speed-position detection is carried out to the moving target detected.According to satellite velocities v _aand the target velocity v detected is calculated by (13) formula _r, the position location of target can be drawn:

$x_0=x+r_c\frac{v_r}{v_a}$

Wherein, r _cfor target is to the oblique distance of platform.

In order to verify the method, the embodiment of the present invention is verified the method by emulation experiment, and its parameter is as shown in table 1 below.

Table 1

Satellite altitude

Satellite velocities

Wavelength

Pulse repetition rate

Vertical parallax

Horizontal base line

Transmitted bandwidth

750km

7492.7m/s

3cm

4464Hz

281.4m

281.4m

60MHz

Improvement factor is defined as:

$\mathrm{IF}\left(\mathrm{dB}\right)=\frac{{\mathrm{SCNR}}_{\mathrm{out}}}{{\mathrm{SCNR}}_{\mathrm{in}}}$

Fig. 2 is the range rate error Performance comparision figure with or without altimetric compensation, Fig. 3 is joint pixel pait and single pixel range rate error comparison diagram.Carry out altimetric compensation and the moving-target range rate error without altimetric compensation as can be seen from Figure 2, due to the elevation phase place that has been coupled in interferometric phase, if do not carry out altimetric compensation, range rate error will increase greatly.And the altimetric compensation method adopting the embodiment of the present invention to provide can significantly improve the precision tested the speed, range rate error is controlled about 0.05, so carrying out in moving target detect process under InSAR configuration that elevation compensates is indispensable step.What Fig. 3 represented is the application condition that when there is registration error, joint pixel pait velocimetry and single pixel method test the speed, and the coherence messages of the neighbor as can be seen from the figure taken full advantage of around object element to be detected due to joint pixel pait method makes rate accuracy higher than single pixel method.

More than describe the flow process of the Ground moving target detection method based on InSAR configuration in detail, the method also can be realized by corresponding device, introduces mechanism and the function of this device below in detail.

A kind of Ground moving target detection device based on InSAR configuration that the embodiment of the present invention provides, as shown in Figure 4, comprising:

Slip pack module 401, the original echoed signals for receiving according to scene irradiated site sets up Sliding spotlight SAR echo model, and the initial SAR image of two dimension slip pack to the single radar in model;

Compressed sensing module 402, for the initial SAR image composition three-dimensional matrice by the multiple radars after imaging, carries out compressed sensing process to three-dimensional matrice section, obtains SAR image;

Registration module 403, for carrying out registration process to SAR image, the same pixel in different SAR image corresponds to same surface units;

Space-time adaptive processing module 404, for carrying out space-time adaptive process to the SAR image after registration;

Elevation phase compensation block 405, for carrying out elevation phase compensation to the SAR image after space-time adaptive process;

Module of target detection 406, carries out target detection for utilizing constant false alarm rate detection technique to the SAR image after elevation phase compensation.

Preferably, registration module 403 specifically for: utilize pixel matching method or subpixel registration method to carry out registration process to SAR image, the precision of image registration is higher than 1/10th resolution elements.

Preferably, space-time adaptive processing module 404, also for: according to the disappear method of clutter of joint pixel pait, clutter recognition process is carried out to SAR image.

Preferably, elevation phase compensation block 405 specifically for:

Carry out elevation phase compensation according to two width SAR image, two width SAR image interferometric phases are:

$\mathrm{\ψ}(i,j)=\mathrm{mean}\left\{\underset{m=-L}{\overset{L}{\mathrm{\Σ}}}\underset{n=-K}{\overset{K}{\mathrm{\Σ}}}\arg \right[s_1^{*}(i+m,j+n)s_2(i+m,j+n)\left]\right\}$

Wherein s ₁(i, j) and s ₂(i, j) represents the complex value of complex pattern 1 and 2 respectively, L and K representative distance to orientation to sliding window size, L=K=3.

SAR image pixel value after elevation phase compensation is:

$\hat{s}(i,j)=s(i,j)\·{\mathrm{\ψ}}^{*}(i,j).$

The Ground moving target detection method and apparatus based on InSAR configuration that the embodiment of the present invention provides, adopts the method for elevation phase compensation to significantly improve rate accuracy, controls range rate error about 0.05.Meanwhile, joint pixel pait is adopted to disappear the method for clutter, can clutter reduction well.

The present invention can have multiple multi-form embodiment; above for Fig. 1-Fig. 4 by reference to the accompanying drawings to technical scheme of the present invention explanation for example; this does not also mean that the instantiation that the present invention applies can only be confined in specific flow process or example structure; those of ordinary skill in the art should understand; specific embodiments provided above is some examples in multiple its preferred usage, and the embodiment of any embodiment the claims in the present invention all should within technical solution of the present invention scope required for protection.

Last it is noted that the foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, although with reference to previous embodiment to invention has been detailed description, for a person skilled in the art, it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1., based on a Ground moving target detection method for InSAR configuration, it is characterized in that, comprising:

Sliding spotlight SAR echo model is set up according to the original echoed signals that scene irradiated site receives, and the initial SAR image of two dimension slip pack to the single radar in model;

By the initial SAR image composition three-dimensional matrice of the multiple radars after imaging, compressed sensing process is carried out to three-dimensional matrice section, obtains SAR image;

Carry out registration process to described SAR image, the same pixel in different SAR image corresponds to same surface units;

Space-time adaptive process is carried out to the SAR image after registration;

Elevation phase compensation is carried out to the SAR image after space-time adaptive process;

Constant false alarm rate detection technique is utilized to carry out target detection to the SAR image after elevation phase compensation.

2. method according to claim 1, is characterized in that, carries out registration process, comprising described SAR image:

Utilize pixel matching method or subpixel registration method to carry out registration process to described SAR image, the precision of image registration is higher than 1/10th resolution elements.

3. method according to claim 1 and 2, is characterized in that, carries out space-time adaptive process, also comprise the SAR image after registration:

According to the disappear method of clutter of joint pixel pait, clutter recognition process is carried out to SAR image.

4. method according to claim 1 and 2, is characterized in that, describedly carries out elevation phase compensation to the SAR image after space-time adaptive process, comprising:

Carry out elevation phase compensation according to two width SAR image, two width SAR image interferometric phases are:

$\mathrm{\ψ}(i,j)=\mathrm{mean}\left\{\underset{m=-L}{\overset{L}{\mathrm{\Σ}}}\underset{n=-K}{\overset{K}{\mathrm{\Σ}}}\arg \right[s_1^{*}(i+m,j+n)s_2(i+m,j+n)\left]\right\}$

Wherein s ₁(i, j) and s ₂(i, j) represents the complex value of complex pattern 1 and 2 respectively, L and K representative distance to orientation to sliding window size, L=K=3.

SAR image pixel value after elevation phase compensation is:

$\hat{s}(i,j)=s(i,j)\·{\mathrm{\ψ}}^{*}(i,j).$

5., based on a Ground moving target detection device for InSAR configuration, it is characterized in that, comprising:

Slip pack module, the original echoed signals for receiving according to scene irradiated site sets up Sliding spotlight SAR echo model, and the initial SAR image of two dimension slip pack to the single radar in model;

Compressed sensing module, for the initial SAR image composition three-dimensional matrice by the multiple radars after imaging, carries out compressed sensing process to three-dimensional matrice section, obtains SAR image;

Registration module, for carrying out registration process to described SAR image, the same pixel in different SAR image corresponds to same surface units;

Space-time adaptive processing module, for carrying out space-time adaptive process to the SAR image after registration;

Elevation phase compensation block, for carrying out elevation phase compensation to the SAR image after space-time adaptive process;

Module of target detection, carries out target detection for utilizing constant false alarm rate detection technique to the SAR image after elevation phase compensation.

6. device according to claim 5, is characterized in that, described registration module specifically for:

Utilize pixel matching method or subpixel registration method to carry out registration process to described SAR image, the precision of image registration is higher than 1/10th resolution elements.

7. the device according to claim 5 or 6, is characterized in that, described space-time adaptive processing module, also for:

According to the disappear method of clutter of joint pixel pait, clutter recognition process is carried out to SAR image.

8. the device according to claim 5 or 6, is characterized in that, described elevation phase compensation block specifically for:

Carry out elevation phase compensation according to two width SAR image, two width SAR image interferometric phases are:

$\mathrm{\ψ}(i,j)=\mathrm{mean}\left\{\underset{m=-L}{\overset{L}{\mathrm{\Σ}}}\underset{n=-K}{\overset{K}{\mathrm{\Σ}}}\arg \right[s_1^{*}(i+m,j+n)s_2(i+m,j+n)\left]\right\}$

Wherein s ₁(i, j) and s ₂(i, j) represents the complex value of complex pattern 1 and 2 respectively, L and K representative distance to orientation to sliding window size, L=K=3.

SAR image pixel value after elevation phase compensation is:

$\hat{s}(i,j)=s(i,j)\·{\mathrm{\ψ}}^{*}(i,j).$